Highhyphen;pressure mechanical instability in closehyphen;packed Hookersquo;shyphen;law crystals

摘要

Lattice dynamics and molecular dynamics are used to study closehyphen;packed crystals with pairwisehyphen;additive Hookersquo;shyphen;law interparticle potentials. Lattice dynamics describes a mechanical softhyphen;mode instability at high pressure. In two dimensions molecular dynamics reveals that a thermodynamic transition, from the triangular closehyphen;packed lattice to the square lattice, occurs before the softhyphen;mode instability density is reached. Similar phenomena occur in the threehyphen;dimensional closehyphen;packed lattices.